Object Analysis

TON 618 is a hyper-luminous, broad-absorption-line quasar located near the North Galactic Pole in the constellation Canes Venatici. It is famous for harboring one of the most massive black holes ever discovered. This "ultramassive" black hole has an estimated mass of 66 billion solar masses.

The black hole at the center of TON 618 is so massive that its event horizon is roughly 390 billion kilometers in diameter—about 40 times the distance from the Sun to Neptune. The quasar itself is located 10.4 billion light-years away and shines with the brightness of 140 trillion suns.

Because it is so distant, we see TON 618 as it appeared when the universe was only a few billion years old. It represents an extreme limit of galactic evolution, raising questions about how such a massive object could grow so quickly in the early history of the cosmos.